(57) A process is described for recovering non-ferrous metal values from a metal-containing
sulphide material containing at least one non-ferrous metal selected from zinc, copper,
lead, cobalt, nickel, silver and gold, as well as iron, comprising leaching the complex
sulphide material under oxidising conditions in a leach stage with an acidic aqueous
chloride lixiviant solution containing magnesium chloride, thereby to solubilise non-ferrous
metal values in the material and to leave a residue comprising iron in oxide or hydrated
oxide form and also sulphur, passing resulting non-ferrous metal-containing leach
liquor to a metal recovery section including a solvent extraction stage in which non-ferrous
metal values are recovered by liquid-liquid extraction using a hydrophobic organic
extractant phase containing a cationic transport agent for non-ferrous metal transport,
recovering from the solvent extraction stage an aqueous magnesium chloride-containing
raffinate, subjecting a portion of the aqueous magnesium chloride-containing raffinate
from the solvent extraction stage to high temperature hydrolysis, thereby liberating
hydrogen chloride and magnesium oxide, recycling another portion of the aqueous magnesium
chloride containing raffinate to the leach stage, recycling liberated hydrogen chloride
to the leach stage, and passing magnesium oxide formed in the high temperature hydrolysis
to the solvent extraction stage for use as neutralising agent for the cationic transport
agent.
|

|